This series of WordPress tutorials cover everything you need to know to get started using WordPress. Courtesy of iThemes (thanks iThemes!).
WordPress 101 (iThemes WordPress Tutorials)
WordPress Codex, Getting Started with WordPress
WordPress Codex, where you can find a lot of great information.
Log-in to Your WordPress Website
How to log in to your WordPress Website.
The WordPress Dashboard (WordPress.tv)
An introduction to your WordPress dashboard.
Jonathan Daggerhart: Introduction to using WordPress (WordPress.tv)
How to Create a Static Page (WordPress Codex)
How to Create New Pages (WordPress Tutorials from iThemes)
Adding an “About Me” (or any other static) page (WordPress.tv)
How to create a post (WordPress Tutorials from iThemes)
Creating A New Post (Blog/Newletter Article) (WordPress.tv)
Adding categories and tags to your posts (WordPress.tv)
How to Use The Media Library (WordPress.tv)
How to Use Widgets (WordPress Codex)
Best Practices For Writing For Online Readers
Great article by Dave Copeland from ReadWriteWeb on best practices for writing on the web.